1. Field of the Invention
The present invention relates to an electromagnetic wave shielding method and an electromagnetic wave shielding window for allowing passing of visible light while reducing passing of an electromagnetic wave to a predetermined level or below, a manufacturing apparatus having the electromagnetic wave shielding window, a transport system having the electromagnetic wave shielding window, and a building construction having the electromagnetic wave shielding window.
2. Description of the Related Art
Recently, emission of unwanted electromagnetic energy has been on the increase with increasing use of electric energy, and adverse effects of such emission to environments are being concerned. The environmental issues posed by an electromagnetic wave include: mutual interference of channels and ghosts of a broadcast wave in regard to wireless communications; the safety of a robot system in regard to a manufacturing apparatus; reliability of a communications network in regard to information processing, etc. In regard to a transport system, electronic control is increasingly involved in the operation control in recent years, and fear for a malfunction is becoming a key issue. In regard to a building construction, a building construction itself has now become a huge antenna as a computer network is provided throughout the construction like the one called today's intelligent building, and because electromagnetic energy is emitted untreated to local residents, influences of electromagnetic wave energy to the bio-ecological system is also becoming a key issue.
Under these circumstances, a window member having an electromagnetic wave shielding ability and a light-transmitting property has been developed. A window member of this type is an electromagnetic wave shielding window disclosed, for example, in JP-A-11-84041, which is formed, as shown in FIG. 18, by disposing a conductive mesh 3 between two transparent substrates 1a and 1b to put these components together, and folding back the edge portion of the conductive mesh 3 that comes out of the transparent substrates 1a and 1b along the edge portion of the transparent substrate 1a to be attached to the transparent substrate with a conductive adhesion tape 5.
Also, an electromagnetic wave shielding window disclosed in JP-A-11-97878 is formed, as shown in FIG. 19, by disposing a transparent conductive film 9 between two transparent substrates 7a and 7b, and laminating a conductive adhesive tape 13 from the edge portion of the transparent conductive film 9 to the edge portion on the main surface of the transparent substrate 7b by way of the end face of the transparent substrate 7b. 
Further, another electromagnetic wave shielding window shown in FIG. 20 is formed by interposing a conductive mesh 17 between plastic plates 15a and 15b, which are a pair of window face members, then applying a conductive coating material 19, such as silver paste, on the edge portions of the pair of plastic plates 15a and 15b and laminating a conductive tape 21 thereon, and fitting a metal window frame member 25 to the outside of the conductive tape 21 through a seal gasket 23.
These electromagnetic wave shielding windows become able to shield an electromagnetic wave at a transparent opening window as the transparent conductive shielding members 3, 9, and 17 are laminated and electrical conductive coupling is provided between the conductive shielding member and the window frame member.
The structure of the conventional electromagnetic wave shielding windows described above, however, has a problem that it becomes a complicated connecting structure due to the need to connect the conductive shielding member to the window frame or the like at the outside. In other words, in the case of the light-transmitting window member with the electromagnetic wave shielding ability shown in FIG. 18, the assembly process demands an elaborate step of folding back the edge portion of the conductive mesh along the edge portion of the transparent substrate.
Also, in the case of the electromagnetic wave shielding window shown in FIG. 19, there is a need for a work to laminate the conductive adhesive tape from the edge portion of the transparent conductive film to the edge portion on the main surface of one transparent substrate by way of the end face of the other transparent substrate.
Further, in the case of the electromagnetic wave shielding window shown in FIG. 20, there is a need for an elaborate work to apply the conductive coating material onto the end faces of a pair of window face members in allowing the conductive coating material to go into a space between the pair of window face members through a capillary phenomenon, so that electrical conductive coupling is provided between the window frame member and conductive fibers.
Moreover, precise and careful assembly is required for any of the electromagnetic wave shielding windows, because in the event that a local void is caused during the assembly of the electromagnetic wave shielding window, an electromagnetic wave leaks through the void and the shielding ability can no longer be ensured.
Furthermore, because an oxide coating film is generally formed or applied on the window frame member attached to a typical manufacturing apparatus, transport system, or building construction, part of the surface of the window frame member has to be scraped off, or tap processing or the like has to be applied in order to bring the window frame member and the conductive shielding member into conduction. Hence, the conventional electromagnetic wave shielding window demands an elaborate connecting work to connect the conductive shielding member and an outside grounding or the like, which poses a problem that not only man-hours needed for the work, but also the manufacturing cost is increased. Also, in a case where the conductive shielding member is connected to the outside grounding or the like through an adhesive agent, the connecting portion may deteriorate with time due to degradation, such as oxidation and corrosion, which poses a problem that a stable electromagnetic wave shielding effect cannot be achieved over a long period.